Toward Multicomponent Single-Atom Catalysis for Efficient Electrochemical Energy Conversion

Abstract

Single-atom catalysts (SACs) have recently emerged as the ultimate solution for overcoming the limitations of traditional catalysts by bridging the gap between homogeneous and heterogeneous catalysts. Atomically dispersed identical active sites enable a maximal atom utilization efficiency, high activity, and selectivity toward the wide range of electrochemical reactions, superior structural robustness, and stability over nanoparticles due to strong atomic covalent bonding with supports. Mononuclear active sites of SACs can be further adjusted by engineering with multicomponent elements, such as introducing dual-metal active sites or additional neighbor atoms, and SACs can be regarded as multicomponent SACs if the surroundings of the active sites or the active sites themselves consist of multiple atomic elements. Multicomponent engineering offers an increased combinational diversity in SACs and unprecedented routes to exceed the theoretical catalytic performance limitations imposed by single-component scaling relationships for adsorption and transition state energies of reactions. The precisely designed structures of multicomponent SACs are expected to be responsible for the synergistic optimization of the overall electrocatalytic performance by beneficially modulating the electronic structure, the nature of orbital filling, the binding energy of reaction intermediates, the reaction pathways, and the local structural transformations. This Review demonstrates these synergistic effects of multicomponent SACs by highlighting representative breakthroughs on electrochemical conversion reactions, which might mitigate the global energy crisis of high dependency on fossil fuels. General synthesis methods and characterization techniques for SACs are also introduced. Then, the perspective on challenges and future directions in the research of SACs is briefly summarized. We believe that careful tailoring of multicomponent active sites is one of the most promising approaches to unleash the full potential of SACs and reach the superior catalytic activity, selectivity, and stability at the same time, which makes SACs promising candidates for electrocatalysts in various energy conversion reactions.

Bimetallic Sites for Catalysis: From Binuclear Metal Sites to Bimetallic Nanoclusters and Nanoparticles

“…The advantages of binuclear bimetallic sites for electrocatalytic oxygen reduction/evolution reactions have been demonstrated with other binuclear bimetallic sites embedded in N-doped carbon matrix, such as the IrCo, CoFe, NiFe, RuCo, and IrFe sites. − In most of the proposed atomic structures of the binuclear sites, the two metal atoms are coordinated by six N atoms and bridged by two N atoms, although there are differences in the synthesis methods among these works. Despite the numerous reports on application of binuclear bimetallic sites for electrocatalytic oxygen reduction/evolution reactions and the similarities in the structure of the active sites, benchmarking of the catalytic performances of various binuclear bimetallic sites under the same testing conditions is urgently needed to achieve a unified understanding on the structure–reactivity relationship in this direction.…”

Investigations on the ORR Catalytic Performance Attenuation of a 1D Fe Single-Atom Catalyst during the Discharge Process

“…As the discharge process proceeds, the numbers and volume of the discharge byproduct continue to increase, leading to further degradation in the ORR catalytic performance of the catalyst. Based on the analyses, it is extremely important to improve the stability of SAC catalysts using multicomponent SAC catalysts to change the connection method of the active sites 32 or introduce heteroatoms with stronger electronegativity to enhance the bond energy of chemical bonds in SAC catalysts, especially Fe−N bonds.…”

Tuning Electrochemical Hydrogen-Evolution Activity of CoMoO4 through Zn Incorporation

“…Electrocatalytic water splitting is a potential approach to convert renewable electricity-generated from renewable energy resources-to hydrogen as a pure, viable, and carbon dioxide-free energy source [3,4]. The efficiency of the water-splitting process is closely dependent on the degree of competence of the electrocatalysts to drive the evolution of the hydrogen (HER) and oxygen (OER) from the medium [5,6]. Noble metal-based electrocatalysts, despite their robust activity, are not sufficiently durable.…”